Centrifugal compressor



' J. GOMBOROW.

CENTRIFUGAL COMPRESSOR.

APPLICATION FILED NOV. 20, 1918.

1,350,927, Patented-Aug. 24,1920.

Inventor; Joel Gom borow,

His o ttoI-ney.

citizen of the nited States; residin JOEL. GOMBOROW, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CENTRIFUGAL COMPRESSOR.

Specification of Letters Patent.

Patented Aug. 21, 1920.

Application filed November 26, 1918. Serial No. 264,221.

To dill 3710112 it may concern:

Be it known that I, JOEL GOMBOROW, a at Lynn, in the county of Essex, State of iIassachusetts, have invented certain new and useful Improvements in Centrifugal Compressors, of which the following is a specification.

The present invention relates to centrifugal compressors comprising an impeller having blades which receive the air, or other gas being handled at their radially lnner ends, impart velocity to it, and then discharge it at their peripheries to stationary discharge vanes wherein a portion of the velocity is converted into pressure.

\Vitlrsuch a machine if we conceive a meridian plane to be passed through the center line of the impeller shaft and-another plane to be passed through the middle of the impeller perpendicular to the shaft, the energy imparted to a particle of air by the rotation of the impeller may be considered to be a function of (1) the radial dis tance from the shaft (2) the angular distance from the meridianplane, and (3) the axial distance from the central perpendicular plane. Usually, however, impellers are built so that energy variations in an angular and in an axial direction are negligible relatively to the energy variations in a radial direction; in other words, cylindrical surfaces co-axial with the shaft may be re arded nearly enough as equipotential sur aces.

Neglecting the effect of gravity, the energy of a particle of air wit in an impeller may be expressed by the formula g zacceleration o gravity in ft. per sec-- ond. But while the total energy'in a article of air may be considered as indepen ent of its angular distance from the imaginar fixedv meridian plane, it will be apparent t at unless the number of impeller blades is very large (theoretically in nite), there will be an appreciable difl'erence of pressure be- -the driving face of a blade and a minimum at the back of it. Now, considering a case a where the exit edges of the impeller blades and the inlet edges of the stationary vanes are both straight and parallel to the shaft, it will be seen that at the instant an im: peller blade passes a discharge vane the pressure between the blade and the vane changes suddenly from a maximum -to a minimum which. gives rise to a considerable shock on the impeller blade, which, if the blade is not firmly anchored or stiffened, may cause it to vibrate. Also since the energy along any concentric circumference substantially constant the maximum pressure at the driving face must be accompanied by a minimum velocity of the air, and the minimum pressure at the back of theblade by a maximum velocity of the air; and the sudden change of this velocity as an impeller blade passes a discharge vane gives rise to an objectionable noise. I

The object of the present invention is to provide an improved arrangement which shape the impeller blades and the vanes that v such edges extend at different angles to the axis of the shaft. To this end I may make the exit edges of the impeller blades extend parallel to the axis of the shaft and the inlet edges of the discharge vanes extend at an angle thereto, or vice. versa; or I may make both such sets of edges extend at angles to. the axis of the shaft but at different angles. By this arrangement the time of the complete crossing of a blade and a vane is materially increased and the crossing is gradual so that the pressures on the vanes are varied gradually. By this means it Will be seen no sudden shock will be imparted to the blades due to their passing quickly from a region of one pressure to a region of a different pressure. Preferably the arrangement is such that the ends of the impeller blades and the ends of the stationary vanes are always overlapping. In actual practice I prefer to make the exit edges of the impeller blades straight or substantially straight and parallel to the axis of the shaft,

and to make .the inlet edges of the discharge veloped top plan view looking down on .center line of the shaft.

1. eferring to the drawing, 5 indicates a shaft carrying an impeller which is provided with blades 6. As shown, the exit edges of these blades are straight and parallel to the Surrounding the impeller are the stationary discharge vanes 7 which are suitably shaped and their inlet edges set at an angle to the center line of the shaft. The radially inneredges of the discharge vanes 7 are thus inclined to the radially outer edges-of the impeller blades 6 and as a result a blade does not pass a vane throughout its axial width at the same instant but passes it gradually. As a result both the shock on the blade and the noise are materially reduced.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, togetherwith the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is 1-- 1. In a centrifugal compressor, an impeller having a set of blades and a set of discharge vanes which surround the impeller, said discharge vanes having substantially the same axial width as the blades and extending radially and circumferentially whereby the fluid discharged to them from the blades is given a combined radial and tangential path, said vanes serving to convert velocity into pressure, the discharge edges of the blades and the inlet edges of the vanes being straight and made to extend at different angles to the axis of the shaft whereby they will cross each other gradually.

2. In a centrifugal compressor, animpeller having a set of blades and a set of discharge vanes which surround the impeller, said discharge vanes having substantially the same axial width as the blades and extending radially and circumferentially whereby the fluid discharged to them from the blades is given a combined radial and tangential path, said vanes serving to convert velocity into pressure, the edges of said sets being straight and arranged with the edges of one of said sets parallel to the axis of the shaft and the edges of the other of said sets at an angle thereto, whereby they will pass each other gradually.

3. In a centrifugal compressor, an im- 7 peller having a set of blades and a set of discharge vanes which surround the impeller, said discharge vanes having substantially the same width as the blades and extending radially and circumferentially whereby the fluid discharged to them from the blades is given a combined radial and tangential path, said vanes serving to convert velocity into pressure, the discharge edges of the impeller blades being substantially parallel to the center line of the shaft, and the inlet edges of the discharge vanes being set at an angle thereto.

4. In a centrifugal compressor, an impeller having straight blades set substantially parallel to the center line of the shaft, and stationary discharge vanes which surround the impeller and extend radially and circumferentially whereby the fluid discharged to them from the impeller is guided in a combined radial and tangential path, 

